This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-032559, filed Feb. 8, 2001, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a wiring member of a suspension for a disc drive incorporated in an information processing apparatus such as a personal computer.
2. Description of the Related Art
A hard disc drive (HDD) for recording and reading information or a rotating magnetic disc or magneto-optical disc has a carriage that can turn around a shaft. This carriage is turned around the shaft by means of a positioning motor. The carriage is provided with an arm (actuator arm), a suspension on the distal end portion of the arm, a head portion including a slider attached to the suspension, etc.
When the disc rotates, the slider on the distal end portion of the suspension is slightly lifted from the surface of the disc, and an air bearing is formed between the disc and the slider. The suspension comprises a base portion including a base plate, a load beam portion formed of a thin precise plate spring, a flexure fixed to the load beam portion by laser welding or the like, etc.
The flexure may be formed variously depending on required specifications. By way of example, there is a newly developed wired flexure designed so that a wiring portion is provided on the surface of a substrate that extends in the longitudinal direction of a load beam portion along it. The wired flexure includes a stainless-steel substrate in the form of a very thin sheet, read and write wires on the substrate, etc. An electrical insulating layer formed of an electrical insulating material such as polyimide is interposed between the substrate and the wires.
One end of each of the reading and writing wires of the wired flexure is connected electrically to a terminal of a slider that is attached to the distal end portion of the flexure. The respective other ends of the read and write wires are connected individually to terminals that are located near the actuator arm, for example.
The thinner the electrical insulating layer of the suspension that is provided with the wired flexure constructed in this manner, the shorter the distance between the substrate and the read wire or between the substrate and the write wire is.
Possibly, therefore, current that causes noise may leak from the write wire, through which a relatively high current flows, toward the read wire. If various stray currents (e.g., looped eddy current) from any regions other than the write wire flow into the read wire, radio interference or so-called crosstalk may be caused in some cases. This interference constitutes a hindrance to the transmission of normal signals.
Leakage of current from the write wire to the substrate may possibly be restrained by removing a part of the substrate (electrically conductive material) at the back of the write wire. If this is done, however, various stray currents from any regions other than the write wire may flow into the read wire through the substrate, in some cases. Thus, the partial removal of the substrate cannot be a drastic measure to counter the leakage of current.
On the other hand, the leakage of current may possibly be restrained by removing a part of the substrate at the back of the read wire. In this case, however, no electrically conductive material (ground surface) exists at the back of the read wire, so that the impedance is higher than in the case where a conductive material exists at the back of the read wire. Thus, it is hard to secure impedance matching with an electrical component connected to the wire, so that signals are subject to substantial distortion.
Based on these circumstances, there is a demand for a wiring member of a suspension for a disc drive that enjoys improved crosstalk characteristic without failing to secure impedance matching of the read wire.
A wiring member according to the present invention comprises a substrate formed of an electrically conductive material such as stainless steel, a read wire provided on an electrical insulating layer on the substrate so as to extend along the substrate, a write wire provided on the electrical insulating layer on the substrate so as to extend along the read wire, and a slit formed between the read and write wires of the substrate so as to extend along the wires and dividing the substrate between a first portion on the read wire side and a second portion on the write wire side.
According to the wiring member of the invention, impedance matching can be secured between the read wire and an electrical component to which the read wire is connected. Further, stray currents can be restrained from flowing into the read wire through the write wire or any other part, so that the crosstalk characteristic can be improved.
Preferably, in the present invention, the slit is situated nearer to the read wire than to the write wire. Since the slit is situated close to the read wire, according to this invention, stray currents can be restrained more effectively from flowing into the read wire.
An example of the substrate is a substrate of a wired flexure carrying a slider thereon. In the wired flexure, according to this invention, impedance matching can be secured between the read wire and an electrical component to which the read wire is connected. Further, stray currents can be restrained from flowing into the read wire through the write wire or any other part, so that the crosstalk characteristic can be further improved.
A part of the substrate may be provided with a connecting portion connecting the first and second portions to each other. According to this invention, the connecting portion on the substrate can accurately regulate the relative positions of the first and second portions.
In the present invention, the read wire may have a portion crossing the slit and overlying the first and second portions, and the read wire may be fixed to both the first and second portions. According to this invention, the first and second portions can be connected mechanically to each other by utilizing a part of the read wire that crosses the slit.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.